Um, hard sci-fi? Some handwavy "upload person to computer" stuff and then "we'll just rearrange the universe over here, don't mind us". I did read it a long time ago, but I don't remember anything that specific in it.
Permutation City is definitely hard sci-fi, albeit less hard than most of Egan's work. Ignoring the "uploading" (it not being the central point of the story, and this not being the place to have that debate), his "dust theory" is very well grounded. That's not to say that I believe it (or that he does, see http://www.gregegan.net/PERMUTATION/FAQ/FAQ.html), but that doesn't automatically qualify it as "magic" either.